Search found 80 matches
- Mon May 18, 2020 1:58 am
- Forum: Hardware
- Topic: ZX81 rebuild
- Replies: 175
- Views: 63901
Re: ZX81 rebuild
I’ve been trying to contact David Husband to ask permission to use the Forth ROM in my emulator. I’m no longer sure who I should be asking. I’ve read the other threads in this group and the above replies regarding the offsets. The fact that David / Skywave Software would have gone on to write Forth ...
- Sat Apr 04, 2020 11:35 am
- Forum: GAMES
- Topic: Tractor Beam - Galaga style game
- Replies: 10
- Views: 13753
Re: Tractor Beam - Galaga style game
Thanks for making this game so polished. I love the attention to the details which really show in the gameplay!
Kevin
Kevin
- Thu Jan 23, 2020 9:27 pm
- Forum: Emulators
- Topic: Emulating musical tones using cassette out - help!
- Replies: 7
- Views: 9184
Re: Emulating musical tones using cassette out - help!
Indeed, the code is used only for the first value in the sound buffer after an IN or OUT. The "newpos" and "subpos" variables are calculated like an integer division and a remainder. So I guess the "subpos" variable smoothes things a bit by not taking the initial value itself, but taking into accou...
- Tue Jan 21, 2020 10:06 pm
- Forum: Emulators
- Topic: Emulating musical tones using cassette out - help!
- Replies: 7
- Views: 9184
Re: Emulating musical tones using cassette out - help!
Hi Mark, All very well described. Thank you. In a real ZX80 or ZX81, it does not matter if the digital output ends up at a logic high or a logic low ... the output at the mic socket will always change towards the 0V / ground level (silence as far as audio systems are concerned) shortly after any act...
- Tue Jan 21, 2020 9:13 am
- Forum: Emulators
- Topic: Emulating musical tones using cassette out - help!
- Replies: 7
- Views: 9184
Re: Emulating musical tones using cassette out - help!
Hi Erik & Mark, Thank you both for responding. I see things more clearer now. Some quick thoughts: 5. If the signal is taken to decrease linearly (rather than exponentially) to the silence level, the beeper volume may perhaps be used to efficiently calculate the range of positions in the waveform wh...
- Sun Jan 19, 2020 7:45 pm
- Forum: Emulators
- Topic: Emulating musical tones using cassette out - help!
- Replies: 7
- Views: 9184
Emulating musical tones using cassette out - help!
Hi All, I’m in the process of adding sound support to my ZX81 iOS emulator app that will be compatible with programs like Kelly Murta's 2005 ZX81 Music Interpreter. The emulator has already had AY support for about 2 years now. To be frank, there are too many holes in my understanding of the mechani...
- Sat Jan 18, 2020 2:11 pm
- Forum: GAMES
- Topic: Cassette60 : the 1K hires games
- Replies: 9
- Views: 6315
Re: Cassette60 : the 1K hires games
Simon wanted a working or not. Not defined that some machines might not work. This to prevent taking back sales. Understood - It is difficult not to agree with his decision. Bigger picture: It would be helpful to the ZX81 community to determine why WRX does not work with all unexpanded ZX81 issues/...
- Sat Jan 18, 2020 10:51 am
- Forum: GAMES
- Topic: Cassette60 : the 1K hires games
- Replies: 9
- Views: 6315
Re: Cassette60 : the 1K hires games
Simon tested several ZX81. Some work, some not. Was there a clear pattern where there same ZX81 computers always failed with all the WRX games? My experience is more to the emulation side. That said, I recommend that you ask Simon to do some controlled tests (no RAM packs, Chroma interfaces etc - j...
- Fri Jan 17, 2020 11:25 pm
- Forum: GAMES
- Topic: Cassette60 : the 1K hires games
- Replies: 9
- Views: 6315
Re: Cassette60 : the 1K hires games
Internal RAM or ULA, I don’t know. OK, so let’s narrow this down a bit: 1) Were the problems limited to WRX games? 2) Did any of the WRX games work on Simon’s ZX81? 3) Did Simon record any video or stills of the display problems? 4) Are there known cases where it works on one unmodified ZX81 withou...
- Fri Jan 17, 2020 10:47 pm
- Forum: GAMES
- Topic: Cassette60 : the 1K hires games
- Replies: 9
- Views: 6315
Re: Cassette60 : the 1K hires games
Any conclusions why they don’t work on all ZX81s? The obvious being RAM packs or modified units with internal RAM not being compatible with WRX - but I think Simon ruled this out.